1. Key Lab of Optoelectronic Technology and Systems of the Education Ministry of China, Chongqing University, Chongqing, China
2. China Academy of Engineering Physics, Institute of Materials, Mianyang, China
3. Department of Electrical and Computer Engineering, University of Massachusetts Lowell, Lowell, MA, USA
4. School of Biomedical Engineering, Sun Yat-Sen University, Shenzhen, China